Influence of climate change on future operation of a complex storage hydropower scheme in the Swiss Alps

For the case study area of the upper Aare River catchment in Switzerland with large mountain glaciers, where a complex storage hydropower scheme is located, the impact of climate change on runoff was simulated. Future runoff was assessed for the ongoing century using the semi-distributed conceptual hydrological modeling approach "Routing System". Glacier mass balance and runoff were computed in hourly time steps for precipitation and temperature distributions. The model was calibrated using ice volume changes and daily runoff at five gauging stations in the catchment area. The scenarios for future climatic conditions up to 2099 were developed from historical temperature and precipitation data series. The herein presented C2SM-ETHZ scenario, neglecting any global greenhouse gas reduction in future, predicts an almost complete de-glacierization of the upper Aare River basin until the end of the century. Runoff from glacier melt will initially slightly increase, followed by a decrease due to important ice mass losses. Total runoff will decrease by 2% until 2050 and by 18% until 2099. Significant decrease of runoff related to glacier melt must be considered for future hydropower management.